1. Field of the Invention
The present invention relates to a process for the preparation of a phosphoric monoester through the phosphorylation of an organic hydroxyl compound. More particularly, the present invention relates to a process for the preparation of a phosphoric monoester which can easily provide a phosphoric ester mixture having a high phosphoric monoester purity, a reduced orthophosphoric acid content, and good odor and hue.
2. Description of the Related Art
Phosphoric esters of organic hydroxyl compounds are used in a wide field as a detergent, a textile treating agent, an emulsifying agent, a rust preventive, a liquid ion exchanger and a medicament.
Although the reaction of an organic hydroxyl compound with phosphorus pentaoxide has been known as an industrial process for the preparation of a phosphoric ester in the prior art, the product of the reaction comprises mainly a nearly equimolar mixture of a phosphoric monoester represented by the following formula (A) and a phosphoric diester represented by the following general formula (B) (hereinafter, this mixture is referred to as xe2x80x9csesquiphosphatexe2x80x9d): 
wherein R represents a residue which is obtained by eliminating one hydroxyl group from an organic hydroxyl compound.
There are great differences in properties between a phosphoric monoester and a phosphoric diester. For example, alkali metal salts and alkanolamine salts of phosphoric monoesters of long-chain alkyl alcohols (e.g., lauryl alcohol) are soluble in water, excellent in foaming power and detergency, less toxic and lowly irritant to the skin to be useful as an excellent detergent, while alkali metal salts and alkanolamine salts of phosphoric diesters of long-chain alkyl alcohols are little soluble in water and exhibit foam inhibiting properties rather than little exhibit a foaming power. Therefore, a sesquiphosphate salt containing a large amount of a phosphoric diester salt is unusable as a highly foaming detergent.
Under these circumstances, the development of a process by which a phosphoric ester mixture having a high phosphoric monoester content can be prepared on an industrial scale safely and easily has been eagerly expected and the following processes have been reported to answer this expectation:
(1) a process which comprises reacting an organic hydroxyl compound with phosphorus oxychloride and hydrolyzing the obtained monoalkyl phosphoro-dichloridate;
(2) a process which comprises adding water to an organic hydroxyl compound and thereafter adding phosphorus pentaoxide to the obtained mixture to conduct phosphorylation with the amount of water preliminarily added being 0.5 to 3 mol per mol of phosphorus pentaoxide;
(3) a process which comprises reacting an organic hydroxyl compound with orthophosphoric acid and phosphorus pentaoxide (Japanese Patent Publication-B 42-6730, published on Mar. 18, 1967);
(4) a process which comprises reacting an organic hydroxyl compound with a condensed phosphoric acid (polyphosphoric acid);
(5) a process which comprises reacting an organic hydroxyl compound with a condensed phosphoric acid (polyphosphoric acid) and then recovering, concentrating and reusing excess phosphoric acid;
(6) a process which comprises reacting an organic hydroxyl compound with a phosphorylating agent comprising phosphorus pentaoxide, phosphoric acid and a polyphosphoric acid under such a condition that phosphoric acid components are excess, adding an organic hydroxyl compound to the obtained reaction mixture to make up to a stoichiometric amount and conducting further phosphorylation [see U.S. Pat. No. 4,350,645 (published on Sep. 21, 1982, assignee: Kao Corporation)]; and
(7) a process which comprises reacting an organic hydroxyl compound with phosphorus pentaoxide in the presence of water while blowing steam into the reaction system.
However, these processes have respective disadvantages as will now be described, being unsatisfactory as industrial processes for the preparation of phosphoric monoesters.
According to the process (1), three mol of hydrogen chloride is generated in order to prepare one mol of a phosphoric monoester. Accordingly, the process (1) is problematic in the disposal of hydrogen chloride and working atmosphere. Further, according to the process (1), an alkyl chloride is formed as a by-product owing to the presence of hydrogen chloride, so that it is difficult to enhance the phosphoric monoester content of the reaction product.
According to the processes (2) and (3), an organic hydroxyl compound comes into direct contact with highly active phosphorus pentaoxide from the first, though a small amount of water or orthophosphoric acid is present in the reaction system. Therefore, a sesquiphosphate containing a phosphoric diester is formed to lower the purity of the reaction product for a phosphoric monoester. Additionally, these processes have a disadvantage in that the phosphoric monoester formed is decomposed to cause the discoloration of the reaction product and the generation of a nasty odor. When an increased amount of water or orthophosphoric acid is used in order to lower the activity of phosphorus pentaoxide, the orthophosphoric acid content of the product is increased. The contamination of the product with orthophosphoric acid has undesirable influences on some fields, so that the use of the product is limited. For example, when monosodium salt of a phosphoric monoester of a long-chain alkyl alcohol is employed for a paste detergent, disodium phosphate is deposited due to the present of a large amount of orthophosphoric acid. The deposition of disodium phosphate is unfavorable in the use of the detergent.
According to the process (4), a phosphoric monoester can be selectively prepared. However, the amount of orthophosphoric acid formed as a by-product is nearly equal to the reciprocal of the average degree of condensation of the polyphosphoric acid used, so that the contamination of the product with orthophosphoric acid is unavoidable. Accordingly, the process (4) has the same problem as that of the processes (2) and (3). Further, the use of a polyphosphoric acid having an extremely high degree of condensation is necessitated in order to decrease the amount of orthophosphoric acid formed as a by-product according to the process (4). However, in the industrial preparation of such a polyphosphoric acid, the reaction system becomes highly viscous and the materials of the reactor are limited, so that the industrial preparation thereof is extremely difficult.
According to the process (5), a phosphoric monoester can be selectively prepared. Further, the process involves the recovery and reutilization of excess phosphoric acid, being industrially advantageous also in this respect. However, the process uses a large amount of phosphoric acid, so that the recovery thereof necessitates the shouldering of various heavy burdens and the use of considerably complicated equipment. Accordingly, the process cannot easily be conducted.
According to the process (6), the organic hydroxyl compound is added in two portions, so that the obtained reaction product has an enhanced ratio of a phosphoric monoester to a phosphoric diester. However, the reaction system tends to become highly viscous under the condition of an excess of the phosphorylating agent i.e., in the early stages of the reaction to necessitate the use of an industrially special reactor. According to the process (6), additionally, the decomposition of the phosphoric monoester formed proceeds, which lowers the yield of the phosphoric monoester and enhances the orthophosphoric acid content of the reaction product. The increase in the orthophosphoric acid content of the reaction product has undesirable influences on some fields, so that the use of the reaction product is limited.
According to the process (7), the ratio of the phosphoric monoester to the phosphoric diester can be enhanced by blowing steam into the reaction system. However, the blowing of steam into the reaction system increases the amount of orthophosphoric acid formed. Accordingly, the process (7) has the same problem as that of the processes (2), (3) and (4).
As described above, the process using phosphorus oxychloride as a phosphorylating agent is problematic in that hydrogen chloride is generated, while that using a polyphosphoric acid is problematic in that orthophosphoric acid is formed as a by-product and that the materials of the reactor are limited. Among the processes using phosphorus pentaoxide, those involving the direct reaction of an organic hydroxyl compound with phosphorus pentaoxide give a sesquiphosphate containing a phosphoric diester, while that of reacting an organic hydroxyl compound with an excess of a phosphorylating agent in order to lower the phosphoric diester content of the reaction product is problematic in that the reaction system becomes viscous to result in difficult stirring and that a large amount of orthophosphoric acid is formed as a by-product.
The industrial processes for the preparation of phosphoric monoesters according to the prior art have been described above, among which those using phosphorus pentaoxide are advantageous in respect of equipment. Therefore, further improvement in the processes using phosphorus pentaoxide has been expected eagerly.
Summary of the Invention
An object of the present invention is to provide an industrial process for the preparation of a phosphoric monoester according to the phosphorus pentaoxide method which gives a reduced amount of orthophosphoric acid formed as a by-product, can give a phosphoric monoester selectively and in an enhanced yield, and is characterized in that the obtained reaction product is excellent in hue and odor.
Another object of the present invention is to provide an industrial process for the preparation of a phosphoric monoester according to the phosphorus pentaoxide method, by which the phosphorylation can be always conducted in a low-viscosity system.
Under the circumstances described above, the present inventors have made extensive studies on the industrial preparation of a phosphoric monoester. As a result of the studies, they have found that a phosphoric ester mixture which has good hue and odor and an enhanced monoester content and is reduced in the amount of phosphoric acid formed as a by-product can be prepared industrially efficiently by preliminarily mixing the whole or part of the phosphorus pentaoxide to be used in the reaction with at least one compound selected from the group consisting of water, phosphoric acid and a polyphosphoric acid to prepare a phosphorylating agent and adding an organic hydroxyl compound to the phosphorylating agent unlike the feeding order of starting materials according to the prior art. The phosphorylating agent described above takes the form of a heterogeneous system wherein part of the phosphorus pentaoxide fed remains undissolved. The present inventors have also found that an objective phosphoric monoester can be prepared without any increase in the viscosity of the reaction system especially by reacting an organic hydroxyl compound preliminarily with the phosphorylating agent of which the amount is less than the stoichiometric one (i.e., with a phosphorylating agent prepared by using part of the phosphorus pentaoxide to be used in the reaction), and adding the balance of phosphorus pentaoxide to the obtained reaction product to make up to a total amount of ca. stoichiometric one. The present invention has been accomplished on the basis of these findings.
Thus, the present invention provides a process for the preparation of a phosphoric monoester by reacting an organic hydroxyl compound with a phosphorylating agent comprising phosphorus pentaoxide and at least one compound selected from the group consisting of water, phosphoric acid and polyphosphoric acid, under such conditions that a) the ratio as defined by formula (I) has a value in the range of from 0.5 to 1.0, and b) the ratio as defined by formula (II) has a value in the range of from 2.8 to 3.2:                                           [                                                                                Molar                    ⁢                                          xe2x80x83                                        ⁢                    amount                    ⁢                                          xe2x80x83                                        ⁢                    of                    ⁢                                          xe2x80x83                                        ⁢                    phosphorylating                                                                                                                    agent                    ⁢                                          xe2x80x83                                        ⁢                    represented                    ⁢                                          xe2x80x83                                        ⁢                    as                    ⁢                                          xe2x80x83                                        ⁢                                          P                      2                                        ⁢                                          O                      5                                                                                            ]                                [                                                                                Molar                    ⁢                                          xe2x80x83                                        ⁢                    amount                    ⁢                                          xe2x80x83                                        ⁢                    of                    ⁢                                          xe2x80x83                                        ⁢                    water                    ⁢                                          xe2x80x83                                        ⁢                    included                                                                                                                    in                    ⁢                                          xe2x80x83                                        ⁢                    the                    ⁢                                          xe2x80x83                                        ⁢                    phosphorylating                    ⁢                                          xe2x80x83                                        ⁢                    agent                                                                                                                    represented                    ⁢                                          xe2x80x83                                        ⁢                    as                    ⁢                                          xe2x80x83                                        ⁢                                          P                      2                                        ⁢                                                                  O                        5                                            ·                                              n                        ⁡                                                  (                                                                                    H                              2                                                        ⁢                            O                                                    )                                                                                                                                          ]                          ⁢                  xe2x80x83                ⁢        and                            (        I        )                                                                                    [                                                                                                    Molar                        ⁢                                                  xe2x80x83                                                ⁢                        amount                        ⁢                                                  xe2x80x83                                                ⁢                        of                        ⁢                                                  xe2x80x83                                                ⁢                        water                                                                                                                                                included                        ⁢                                                  xe2x80x83                                                ⁢                        in                        ⁢                                                  xe2x80x83                                                ⁢                        the                                                                                                                                                phosphorylating                        ⁢                                                  xe2x80x83                                                ⁢                        agent                                                                                                                                                represented                        ⁢                                                                              xe2x80x83                                                    ⁢                                                      xe2x80x83                                                                          ⁢                        as                        ⁢                                                  xe2x80x83                                                ⁢                                                  P                          2                                                ⁢                                                                              O                            5                                                    ·                                                      n                            ⁡                                                          (                                                                                                H                                  2                                                                ⁢                                O                                                            )                                                                                                                                                                          ]                            +                              [                                                                                                                              Molar                          ⁢                                                      xe2x80x83                                                    ⁢                          amount                                                ⁢                                                  xe2x80x83                                                                                                                                                                        of                        ⁢                                                  xe2x80x83                                                ⁢                        organic                                                                                                                        hydroxyl                                                                                                  compound                                                                      ]                                                    [                                                                                          Molar                      ⁢                                              xe2x80x83                                            ⁢                      amount                      ⁢                                              xe2x80x83                                            ⁢                      of                      ⁢                                              xe2x80x83                                            ⁢                      phosphorylating                                                                                                                                  agent                      ⁢                                              xe2x80x83                                            ⁢                      represented                      ⁢                                              xe2x80x83                                            ⁢                      as                      ⁢                                              xe2x80x83                                            ⁢                                              P                        2                                            ⁢                                              O                        5                                                                                                        ]                                ⁢                      xe2x80x83                    .                ⁢                  xe2x80x83                                    (        II        )            
The term xe2x80x9cmolar amount of organic hydroxyl compoundxe2x80x9d means the equivalent of hydroxyl group(s) derived from the organic hydroxyl compound.
According to this process, the synthesis of phosphoric esters (phosphorylation) having a high phosphoric monoester purity can be generally achieved substantially only by the above one step.
Further, the present invention provides a process for the preparation of a phosphoric monoester comprising:
(1) a first step of reacting an organic hydroxyl compound with a phosphorylating agent comprising phosphorus pentaoxide and at least one compound selected from the group consisting of water, phosphoric acid and polyphosphoric acid, under such conditions that a) the ratio as defined by formula (I) has a value in the range of from 0.5 to 1.0 and b) the ratio as defined by formula (II) has a value in the range of from exceeding 3.2 up to 6.4, and
(2) a second step, wherein phosphorus pentaoxide is added in such an amount that the ratio represented by formula (II) has a value in the range of from 2.8 to 3.2.
According to this process, the synthesis of phosphoric esters (phosphorylation) having a high phosphoric monoester purity can be generally achieved substantially only by the above two steps.
In the formulae (I) and (II), the phosphorylating mixture comprising phosphorus pentaoxide and polyphosphoric acid and/or phosphoric acid (i.e., orthophosphoric acid) and/or water is formally treated as P2O5.n(H2O) and called as xe2x80x9cphosphorylating agentxe2x80x9d. The molar amount of phosphorylating agent as defined in the formulae (I) and (II) represents the amount (mol) of P2O5 unit(s) derived from the phosphorylating agent, which is introduced into the reaction system as the starting material. The molar amount of water as defined in the formulae (I) and (II) represents the amount (mol) of water (H2O) derived from the phosphorylating agent, which is introduced into the reaction system as the starting material. The water includes the bound water in the polyphosphoric acid (P2O5.xH2O) and/or orthophosphoric acid (1/2(P2O5.3H2O)), and free water.
In other words, the present invention relates to a process for the preparation of a phosphoric ester characterized by reacting a phosphorylating agent prepared by mixing phosphorus pentaoxide with water, phosphoric acid or polyphosphoric acid or a mixture of them in such a way that the value represented by the following formula (i):                               [                                                                      Molar                  ⁢                                      xe2x80x83                                    ⁢                  number                  ⁢                                      xe2x80x83                                    ⁢                  of                  ⁢                                      xe2x80x83                                    ⁢                  phosphorylating                                                                                                      agent                  ⁢                                      xe2x80x83                                    ⁢                  calculated                  ⁢                                      xe2x80x83                                    ⁢                  as                  ⁢                                      xe2x80x83                                    ⁢                                      P                    2                                    ⁢                                      O                    5                                                                                ]                          [                                                                      Molar                  ⁢                                      xe2x80x83                                    ⁢                  number                  ⁢                                      xe2x80x83                                    ⁢                  of                  ⁢                                      xe2x80x83                                    ⁢                  water                  ⁢                                      xe2x80x83                                    ⁢                  including                  ⁢                                      xe2x80x83                                    ⁢                                                            n                      ⁢                      H                                        2                                    ⁢                  O                                                                                                      in                  ⁢                                      xe2x80x83                                    ⁢                  the                  ⁢                                      xe2x80x83                                    ⁢                  case                  ⁢                                      xe2x80x83                                    ⁢                  that                  ⁢                                      xe2x80x83                                    ⁢                  phosphorylating                                                                                                      agent                  ⁢                                                            xe2x80x83                                        ⁢                                          xe2x80x83                                                        ⁢                  is                  ⁢                                                            xe2x80x83                                        ⁢                                          xe2x80x83                                                        ⁢                  represented                  ⁢                                      xe2x80x83                                    ⁢                  by                  ⁢                                      xe2x80x83                                    ⁢                                      P                    2                                    ⁢                                                            O                      5                                        ·                                                                  n                        ⁢                        H                                            2                                                        ⁢                  O                                                              ]                                    (        i        )            
will be from 0.5 to 1.0 with an organic hydroxyl compound under such a condition that the value represented by the following formula (ii):                                           [                                                                                Molar                    ⁢                                          xe2x80x83                                        ⁢                    number                    ⁢                                          xe2x80x83                                        ⁢                    of                    ⁢                                          xe2x80x83                                        ⁢                    water                                                                                                                    including                    ⁢                                          xe2x80x83                                        ⁢                                                                  n                        ⁢                        H                                            2                                        ⁢                    O                    ⁢                                          xe2x80x83                                        ⁢                    in                    ⁢                                          xe2x80x83                                        ⁢                    the                    ⁢                                          xe2x80x83                                        ⁢                    case                                                                                                                    that                    ⁢                                          xe2x80x83                                        ⁢                    phosphorylating                                                                                                                    agent                    ⁢                                          xe2x80x83                                        ⁢                    is                    ⁢                                          xe2x80x83                                        ⁢                    represented                    ⁢                                          xe2x80x83                                        ⁢                    by                                                                                                                                          P                      2                                        ⁢                                                                  O                        5                                            ·                      n                                        ⁢                                          xe2x80x83                                        ⁢                                          H                      2                                        ⁢                    O                                                                        ]                    +                      [                                                                                Molar                    ⁢                                          xe2x80x83                                        ⁢                    number                                                                                                                    of                    ⁢                                          xe2x80x83                                        ⁢                    organic                                                                                                hydroxyl                                                                              compound                                                      ]                                    [                                                                      Molar                  ⁢                                      xe2x80x83                                    ⁢                  number                  ⁢                                      xe2x80x83                                    ⁢                  of                  ⁢                                      xe2x80x83                                    ⁢                  phosphorylating                  ⁢                                      xe2x80x83                                    ⁢                  agent                                                                                                      calculated                  ⁢                                      xe2x80x83                                    ⁢                  as                  ⁢                                      xe2x80x83                                    ⁢                                      P                    2                                    ⁢                                      O                    5                                                                                ]                                    (        ii        )            
will be from 2.8 to 6.4, and, if necessary, further adding phosphorus pentaoxide thereto in such a way that the value represented by the following formula (iii):                                           [                                                                                Molar                    ⁢                                          xe2x80x83                                        ⁢                    number                    ⁢                                          xe2x80x83                                        ⁢                    of                    ⁢                                          xe2x80x83                                        ⁢                    water                                                                                                                    including                    ⁢                                          xe2x80x83                                        ⁢                                                                  n                        ⁢                        H                                            2                                        ⁢                    O                    ⁢                                          xe2x80x83                                        ⁢                    in                    ⁢                                          xe2x80x83                                        ⁢                    the                                                                                                                    case                    ⁢                                          xe2x80x83                                        ⁢                    that                    ⁢                                          xe2x80x83                                        ⁢                    the                    ⁢                                          xe2x80x83                                        ⁢                    whole                                                                                                                    phosphorylating                    ⁢                                          xe2x80x83                                        ⁢                    agent                    ⁢                                          xe2x80x83                                        ⁢                    is                                                                                                                                          xe2x80x83                                        ⁢                                          represented                      ⁢                                              xe2x80x83                                            ⁢                      by                      ⁢                                              xe2x80x83                                            ⁢                                              P                        2                                            ⁢                                                                        O                          5                                                ·                        n                                            ⁢                                              xe2x80x83                                            ⁢                                              H                        2                                            ⁢                      O                                                                                            ]                    +                      [                                                                                Molar                    ⁢                                          xe2x80x83                                        ⁢                    number                                                                                                                    of                    ⁢                                          xe2x80x83                                        ⁢                    organic                                                                                                hydroxyl                                                                              compound                                                      ]                                    [                                                                      Molar                  ⁢                                      xe2x80x83                                    ⁢                  number                  ⁢                                      xe2x80x83                                    ⁢                  of                  ⁢                                      xe2x80x83                                    ⁢                  the                  ⁢                                      xe2x80x83                                    ⁢                  whole                  ⁢                                      xe2x80x83                                    ⁢                  phosphorylating                                                                                                      agent                  ⁢                                      xe2x80x83                                    ⁢                  calculated                  ⁢                                      xe2x80x83                                    ⁢                  as                  ⁢                                      xe2x80x83                                    ⁢                                      P                    2                                    ⁢                                      O                    5                                                                                ]                                    (        iii        )            
will be from 2.8 to 3.2 with respect to the total feeds to conduct a reaction.
The phosphorylating agent preferably comprises phosphorus pentaoxide and at least one compound selected from the group consisting of water and phosphoric acid.
The phosphorylating agent may be one prepared by mixing phosphorus pentaoxide with at least one compound selected from the group consisting of water, phosphoric acid and polyphosphoric acid either at 100xc2x0 C. for up to 4 hours or at 50xc2x0 C. for up to 10 hours. The phosphorylating agent thus prepared is heterogeneous owing to the presence of phosphorus pentaoxide or its hydrate.
The reaction product obtained by the above process is preferably subjected to hydrolysis and/or deodorization.
The organic hydroxyl compound is desirably a linear or branched, saturated or unsaturated alcohol having 6 to 30 carbon atoms, an adduct of a linear or branched, saturated or unsaturated alcohol having 6 to 30 carbon atoms with 1 or more alkylene oxide(s), wherein the alkylene oxide has 2 to 4 carbon atoms and the number of alkylene oxide molecules added is 1 to 100, or an adduct of an alkylphenol, wherein the alkyl moiety has 6 to 20 carbon atoms, with 1 or more alkylene oxide(s), wherein the alkylene oxide has 2 to 4 carbon atoms and the number of alkylene oxide molecules added is 1 to 100.
Furthermore, the present invention provides a phosphoric monoester obtainable by the process according to the present invention.
The present invention will now be described in detail.
The phosphorus pentaoxide in the present invention is a compound also called xe2x80x9cphosphoric acid anhydridexe2x80x9d and its molecular formula is P4O10 or P2O5.
The phosphoric acid in the present invention refers to orthophosphoric acid represented by the following formula (C): 
The phosphoric acid is generally available in the market as an aqueous solution of phosphoric acid having a concentration of less than 100% by weight in terms of orthophosphoric acid equivalent (i.e., calculated as H3PO4). The concentration is not particularly limited, but is preferably 70 to 90% by weight.
The polyphosphoric acid is a condensate of orthophosphoric acid represented by the above formula (C), and has a pyrophosphate bond(s) (Pxe2x80x94Oxe2x80x94P) in the molecule. The polyphosphoric acid is generally one member selected from the group consisting of linear condensed phosphoric acids represented by formula (F) which will be described below, branched condensed phosphoric acids, cyclic condensed phosphoric acids and cyclic condensed phosphoric acids having a side chain, or a mixture of two or more of them. The polyphosphoric acid may also contain, as one component thereof, orthophosphoric acid represented by the above formula (C). Examples of the linear condensed phosphoric acids include pyrophosphoric acid represented by formula (D) which will be described below and tripolyphosphoric acid represented by formula (E) which will be described below. Examples of the branched condensed phosphoric acids, cyclic condensed phosphoric acids and cyclic condensed phosphoric acids having a side chain include compounds represented by the following formulae (G), (H) and (I) respectively: 
Polyphosphoric acid is a phosphoric acid having a concentration of 100% by weight or above in terms of orthophosphoric acid equivalent (i.e., calculated as H3PO4) and has a homogeneous transparent appearance. The phosphoric acid concentration of the polyphosphoric acid to be used in the present invention is preferably 100 to 120% by weight, though it is not particularly limited.
The organic hydroxyl compound to be used in the present invention is preferably an organic monohydroxyl compound represented by the formula: ROH, though it is not limited thereto as long as it is an organic hydroxyl compound having a hydroxyl group(s). Examples thereof include linear or branched, saturated or unsaturated alcohols having 6 to 30, preferably 8 to 24 carbon atoms, adducts of the alcohols with an alkylene oxide(s) (wherein the alkylene oxide has 2 to 4 carbon atoms and the number of alkylene oxide molecules added is 1 to 100), and adducts of alkylphenols (wherein the alkyl moiety has 6 to 20 carbon atoms) with an alkylene oxide(s) (wherein the alkylene oxide has 2 to 4 carbon atoms and the number of alkylene oxide molecules added is 1 to 100).
Specific examples of the organic hydroxyl compound include octanol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, stearyl alcohol, 2-ethylhexanol, isooctanol, isononanol, isodecanol, isotridecanol and synthetic alcohols such as Oxo alcohol (a product of Nissan Chemical Industry Co. Ltd.), Diadol (a product of Mitsubishi Chemical Co. Ltd.), Dobanol (a product of Mitsubishi Petrochemical Co. Ltd.), Linevol (a product of Showa Shell Chemical Co. Ltd.), Neodol (a product of Shell) and Lial (a product of Eni Chem).
In the present invention, one of these organic hydroxyl compounds or a mixture of two or more of them may be used.
According to the present invention, first, a phosphorylating agent is prepared by mixing phosphorus pentaoxide with at least one compound selected from the group consisting of water, phosphoric acid and polyphosphoric acid in such a way that the ratio as defined by the above formula (I) has a value in the range of from 0.5 to 1.0, preferably from 0.55 to 0.9, still more preferably from 0.60 to 0.85. It is preferable to mix phosphorus pentaoxide with water and/or phosphoric acid, particularly preferably with an aqueous solution of phosphoric acid.
The phosphorylating agent thus prepared contains 0.5 to 1.0 mol of P2O5 unit per mol of water included in the phosphorylating agent represented as P2O5.n(H2O). When the value is less than 0.5, the reaction of an organic hydroxyl compound with the resulting phosphorylating agent will give an increased amount of orthophosphoric acid owing to the high water content of the phosphorylating agent. On the contrary, when the value exceeds 1.0, the resulting phosphorylating agent contains highly active phosphorus pentaoxide as such, so that the reaction of an organic hydroxyl compound with the phosphorylating agent will be liable to give sesquiphosphate; and the phosphorylating agent will be viscous to make the operations in the preparations of the phosphorylating agent and the phosphoric monoester difficult.
The order of feeding the starting materials in the preparation of the phosphorylating agent is not particularly limited as far as the final composition satisfies the requirement with respect to the ratio as defined by formula (I). However, it is preferable to add phosphorus pentaoxide gradually to the other material(s) (water, phosphoric acid and/or polyphosphoric acid), because phosphorus pentaoxide generates heat when mixed with water.
The phosphorylating agent according to the present invention may be heterogeneous. In other words, in the present invention, phosphorus pentaoxide may be merely mixed with one compound selected from the group consisting of water, phosphoric acid and polyphosphoric acid. That is, it is not necessitated that they are reacted each other to give a completely homogeneous polyphosphoric acid. In order to prepare a completely homogeneous polyphosphoric acid, the starting material mixture for the phosphorylating agent must be stirred at high temperature or must be aged, and, therefore, another vessel for preparing the phosphorylating agent is necessitated in addition to the reaction vessel in some case.
The phosphorylating agent prepared by mixing phosphorus pentaoxide with at least one compound selected from the group consisting of water, phosphoric acid and polyphosphoric acid can be used as such, i.e., in a heterogeneous state, in the phosphorylation of an organic hydroxyl compound. It is unnecessary to age the phosphorylating agent by heating prior to the use in the phosphorylation. However, the phosphorylating agent may be stirred under heating to suit the convenience of the reaction. The phosphorylating agent cannot be generally converted into a wholly homogeneous polyphosphoric acid even by stirring either at 90xc2x0 C. for about 5 hours or at 50xc2x0 C. for about 10 hours. The insoluble matter in this case is believed to be phosphorus pentaoxide hydrate.
In order to attain the effect of the present invention more effectively, it is desirable that the amount of phosphorus pentaoxide to be used in this step is at least 30 mole %, more desirably at least 60 mole %, most desirably at least 70 mole % based on the whole amount of the phosphorylating agent calculated as P2O5 unit(s).
According to a first embodiment of the present invention, the phosphorylating agent prepared above is reacted with an organic hydroxyl compound under such a condition that the value represented by the above formula (II) ranges from 2.8 to 3.2, which means that phosphorylating agent (calculated as P2O5 unit(s)) is initially fed in an amount of at least about 0.91 mol per 2 equivalents of hydroxyl groups derived from the organic hydroxyl compound (i.e., in an amount of at least about 91% of the required theoretical amount). When the value represented by the above formula (II) is less than 2.8, which means the presence of an excess of phosphorylating agent, excess phosphorylating agent will be finally converted into orthophosphoric acid, so that the resulting reaction product will contain an increased amount of orthophosphoric acid unfavorably. Further, when the reaction is conducted under such a condition that the ratio as defined by the above formula (II) is less than 2.8, sesquiphosphate is formed with the formation of orthophosphoric acid as a by-product to fail in enhancing the monoester content of the reaction product.
The insolubles contained in the phosphorylating agent according to the present invention may dissolve in the reaction system with the advance of the reaction between the organic hydroxyl compound with the phosphorylating agent.
The phosphorylation under such a condition that the ratio as defined by the above formula (II) ranges from 2.8 to 3.2 is conducted under stirring at generally 30 to 100xc2x0 C., preferably 50 to 90xc2x0 C. for generally 0.1 to 10 hours, preferably 0.1 to 8 hours. When the reaction is conducted under the conditions described above, the reaction will be fully attained without the deterioration of the organic hydroxyl compound.
In the present invention, when an organic hydroxyl compound is reacted with the phosphorylating agent under such a condition that the ratio as defined by the above formula (II) ranges from 2.8 to 3.2, the phosphorylation can be generally attained substantially only by this step. In this case, however, the viscosity of the reaction system sometimes increases during the reaction to necessitate the use of a reactor such as kneader suitable for a highly viscous fluid. Therefore, the second embodiment of the present invention which will be described below in detail is more preferable than the first embodiment of the present invention.
According to a second embodiment of the sent invention, the phosphorylating agent is reacted with an organic hydroxyl compound in a first step under such a condition that the ratio as defined by the above formula (II) ranges from higher than 3.2 to 6.4, which means that phosphorylating agent (calculated as P2O5 unit(s)) is initially fed in an amount of at least 0.37 mol per 2 equivalents of hydroxyl groups derived from the organic hydroxyl compound (i.e., in an amount of at least 37% of the required theoretical amount). When the first step of the reaction is conducted under such a condition that the ratio as defined by the above formula (II) exceeds 6.4, a large amount of unreacted alcohol remains in the reaction system. In this case, the reaction can be advanced by adding phosphorus pentaoxide to the resulting reaction system after the completion of the reaction of the first step. However, a large amount of phosphorus pentaoxide must be added to the reaction system to advance the reaction, which causes increase in the amount of sesquiphosphate formed to lower the purity of the reaction product for the phosphoric monoester unfavorably. The first step is conducted under such a condition that the ratio as defined by the above formula (II) has a value in the range of preferably from 3.5 to 5.5, still more preferably from 4.0 to 5.0.
The insolubles contained in the phosphorylating agent according to the present invention may dissolve in the reaction system with the advance of the reaction between the organic hydroxyl compound with the phosphorylating agent.
The phosphorylation of the first step is conducted under stirring at generally 30 to 100xc2x0 C., preferably 50 to 90xc2x0 C. for generally 0.1 to 10 hours, preferably 0.1 to 8 hours. When the reaction is conducted under such conditions, the reaction will be fully attained without the deterioration of the organic hydroxyl compound.
According to the second embodiment of the present invention, after the completion of the reaction of the first step, phosphorus pentaoxide in such an amount that the ratio as defined by the above formula (II) ranges from 2.8 to 3.2 with respect to the total feeds of the starting materials is added to the reaction system to conduct further phosphorylation. That is, when the phosphorylation of an organic hydroxyl compound is conducted under such a condition that the ratio as defined by the above formula (II) ranges from 2.8 to 3.2 (i.e., the first embodiment of the present invention), additional phosphorus pentaoxide need not be added for further phosphorylation, while when the phosphorylation is conducted under such a condition that the ratio as defined by the above formula (II) exceeds 3.2 but is up to 6.4 (i.e., the first step of the second embodiment of the present invention), phosphorus pentaoxide in such an amount that the ratio as defined by the above formula (II) will be in the range of from 2.8 to 3.2 is additionally added to the reaction system to conduct further phosphorylation (the second step of the second embodiment of the present invention).
When the reaction of the second step is conducted under such a condition that the ratio as defined by the above formula (II) exceeds 3.2, the reaction will not be completed to make unreacted organic hydroxyl compound remain in the reaction system, while when it is conducted under such a condition that the ratio is less than 2.8, excess phosphorylating agent will remain in the reaction system finally as orthophosphoric acid. Both of the cases are unfavorable.
The phosphorus pentaoxide for the reaction of the second step may be added by any of batchwise and semibatchwise methods. The latter is preferable to prevent local reaction. The semibatchwise addition may be conducted by a stepwise or continuous method or a combination of both of them.
There may occurs an idea that POCl3, poly-phosphoric acid or a mixture of phosphorus pentaoxide with water is added as the phosphorylating agent for the second stage of the reaction. However, the addition of POCl3 has a disadvantage of generating hydrogen chloride as a by-product, while the use of the other phosphorylating agents has a disadvantage of generating orthophosphoric acid as a by-product. Surprisingly, the addition of phosphorus pentaoxide as it is does not increase the amount of the phosphoric diester formed and can prevent the formation of orthophosphoric acid as a by-product. Further, the addition thereof can enhance the conversion by virtue of the high phosphorylating power of phosphorus pentaoxide.
After the addition of phosphorus pentaoxide, the resulting mixture is subjected to the reaction under stirring at a temperature of generally 40 to 120xc2x0 C., preferably 60 to 100xc2x0 C. for generally 1 to 24 hours, preferably 2 to 12 hours. When the reaction is conducted under such conditions, the reaction will effectively advance, and, therefore, the conversion of the organic hydroxyl compound will be sufficiently high and the decomposition of phosphoric esters formed will not be liable to proceed.
Among various embodiments according to the present invention, an embodiment is preferable, which comprises conducting the reaction of the first step under such a condition that the ratio as defined by the above formula (II) exceeds 3.2 but is up to 6.4, preferably be 3.5 to 5, and thereafter adding phosphorus pentaoxide in such an amount that the ratio as defined by the above formula (II) ranges from 2.8 to 3.2, preferably 2.9 to 3.1 to the reaction system to conduct further phosphorylation. According to this embodiment, the phosphorylation can be generally achieved substantially only by the above two steps. When the phosphorylation is conducted according to this embodiment, the viscosity increase of the reaction system can be prevented during the reaction to dispense with an equipment such as an intensive mixer.
Although the reaction product (phosphoric ester mixture) prepared by the above process can be used as such, it is preferable for some uses that the reaction product be subjected to the following post-treatment. Specifically, when a phosphoric ester mixture containing a compound having a pyrophosphate bond such as one represented by the following formula (J) is used in the preparation of toiletries, the resulting toiletries exhibit poor properties: 
wherein X represents a hydrogen atom or a residue obtained by eliminating one hydroxyl group from an organic hydroxyl compound. Therefore, it is preferable that the phosphoric ester mixture be subjected to hydrolysis to cleave the pyrophosphate bond.
The hydrolysis is preferably conducted by adding 1 to 10% by weight (based on the obtained reaction product) of water to the reaction product (phosphoric ester mixture) and keeping the resulting mixture at 60 to 100xc2x0 C.
The phosphoric ester mixtures each comprising a phosphoric monoester prepared according to the process of the present invention have relatively good odor. In order to result in a further improvement of the odor, especially in cases of phosphoric monoesters each having a long-chain alkyl group, it is preferable that the phosphoric ester mixture be subjected to deodorization. Although the deodorization may be conducted by any of steam distillation, extraction, crystallization and so forth, steam distillation is preferable with that using a thin film being still more preferable.
The phosphoric monoesters prepared by the process of the present invention and salts thereof can be used in a wide field as a detergent, a textile treatment agent, an emulsifying agent, a rust preventive, a liquid ion exchanger, a medicament or the like. The salts of the monoesters includes salts thereof with alkali metals, alkaline earth metals, alkanolamines, basic amino acids and so forth.
For example, in the preparation of a detergent composition containing a phosphoric monoester according to the present invention or a salt thereof, it is preferable that the monoester or salt be used in an amount of 2 to 60% by weight, particularly 10 to 40% by weight based on the whole weight of the composition. In the preparation of the detergent composition, various surfactant which are commonly used in the preparation of detergent compositions may be optionally used in addition to the above phosphoric monoester or the salt.
Examples of the anionic surfactant usable in this case include sulfate, sulfonate and carboxylate type surfactants. Specific examples of the sulfate and sulfonate type surfactants include salts of alkyl sulfates, salts of polyoxyethylene alkyl sulfates; and sulfosuccinate, taurate, isethionate and xcex1-olefin sulfonate type surfactants, while those of the carboxylate type surfactant include fatty acid soaps, ether carboxylate type surfactants and acylated amino acid type surfactants.
Examples of the amphoteric surfactant usable in the above case include carbobetaine type, phosphobetaine type, sulphobetaine type and imidazolinium betaine type surfactants.
Examples of the nonionic surfactant usable therein include polyoxyalkylene addition type, polyoxypropylene-polyoxyethylene addition type, amine oxide type and mono- and di-ethanolamide type surfactants; sorbitan fatty acid esters and adducts thereof with ethylene oxide; glycerol fatty acid esters and adducts thereof with ethylene oxide; sucrose esters and adducts thereof with ethylene oxide; alkylsaccharide type surfactants and adducts thereof with ethylene oxide; and N-polyhydroxy-alkylfatty acid amide type surfactants.
Examples of the cationic surfactant usable therein include quaternary ammonium salts of linear or branched mono- or di-alkyl addition type and adducts thereof wherein alkylene oxide molecules are added to the alkyl group.
These surfactants are each used alone or as a mixture of two or more of them. The amount of the surfactant is preferably 0.1 to 60% by weight, particularly preferably 1 to 50% by weight based on the whole weight of the detergent composition, though the amount varies depending upon the form of the composition.
The detergent composition containing a phosphoric monoester according to the present invention may further contain one or more conventional components for detergent compositions in addition to the above surfactant components so far as the effects of the phosphoric monoester according to the present invention are not impaired. The conventional components include polyhydric alcohols, e.g., ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycols wherein the degree of polymerization is 4 or above, propylene glycol, dipropylene glycol, polypropylene glycols wherein the degree of polymerization is 3 or above, butylene glycols (such as 1,3-butylene glycol and 1,4-butylene glycol), glycerol, diglycerol, polyglycerols wherein the degree of polymerization is 3 or above, sugar alcohols (such as sorbitol, mannitol, xylitol and maltitol), adducts of glycerols with ethylene oxide (hereinafter abbreviated to xe2x80x9cEOxe2x80x9d) and/or propylene oxide (hereinafter abbreviated at xe2x80x9cPOxe2x80x9d), adducts of sugar alcohols with EO and/or PO, saccharides (such as galactose, glucose, fructose, sucrose, maltose and lactose) and adducts thereof with EO and/or PO, and glycosides (such as methyl glycoside and ethyl glycoside) and adducts thereof with EO and/or PO; oil components, e.g., hydrocarbons (such as liquid paraffin, squalane, vaseline and solid paraffin), natural fats and oils (such as olive oil, jojoba oil, evening primrose oil, coconut oil and beef tallow), ester oils (such as isopropyl myristate, cetyl isooctanoate and neopentyl glycol dicaprate), silicone oils (such as methyl silicone and methyl phenyl silicone), and higher fatty acids (such as isostearic acid and oleic acid); drugs, e.g., vitamines, antimicrobials (such as triclosan and trichlorocarban), anti-inflammatories (such as dipotassium glycyrrhetinate and tocopherol acetate), anti-dandruff agents (such as zinc pyrithione and Octopirox), activators, refrigerants (such as menthol), and ultraviolet absorbers; water swelling clayey minerals, e.g., montmorillonite, saponite, hectorite, veegum, kunipia, smecton; polymers, e.g., polysaccharides (such as carrageenan, xanthan gum, sodium alginate, pullulan, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose) and synthetic polymers (such as carboxyvinyl polymer and polyvinyl pyrrolidone); pigments, e.g., inorganic pigments (such as titanium oxide, kaolin, mica, sericite, zinc white and talc) and powdery polymers (such as polymethyl methacrylate and nylon powder); antiseptics, e.g., methyl paraben and butyl paraben; viscosity modifiers, e.g, inorganic salts, polyethylene glycol stearate and ethanol; pearl ingredients; perfumes; dyestuffs; and antioxidants.
The detergent composition can be prepared by a conventional process. Although the detergent composition may take any form selected from among liquid, paste, solid, powder and so forth, it is desirable that the composition takes a liquid or pasty form.
According to the process for the preparation of a phosphoric monoester in the present invention, a phosphoric ester mixture which has an enhanced purity for a monoester and is reduced in the orthophosphoric acid (by-product) content can be prepared extremely easily. Further, the present invention enables the industrial preparation of a phosphoric monoester excellent in odor and hue.
Although the reason why an excellent phosphoric monoester as described above can be prepared by the process of the present invention has not been elucidated as yet, it is presumed to be as follows: the direct reaction of an organic hydroxyl compound with highly active phosphorus pentaoxide gives diester and triester; in the present invention, however, phosphorus pentaoxide is preliminarily reacted with water, so that the activity of phosphorus pentaoxide is controlled to thereby give monoester preferentially. Further, with respect to the qualities, the direct contact of an organic hydroxyl compound or phosphoric esters with highly active phosphorus pentaoxide is prevented in the present invention to therefore give a reaction product excellent in odor and hue.
The liquid detergent composition containing a phosphoric monoester prepared by the process of the present invention does not harm the skin or hair and is excellent in ability to foam and stability, so that it can be used as a detergent component for a product which comes into direct contact with the skin for a long time, for example, kitchen detergent, as well as a shampoo and a body shampoo.